Archived

Avalanche Forecast

Apr 2nd, 2012–Apr 3rd, 2012

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Kananaskis.

Solar radiation could be intense on Tuesday which will lead to a rise in avalanche danger through the day. Wind slabs, cornices and deeper weak layers will be easier to trigger as the day goes on. Loose wet slides are also a strong possibility.

Confidence

Good - Timing or intensity of solar radiation is uncertain

Weather Forecast

A warm, sunny and very windy day is expected on Tuesday. Solar radiation will be significant and freezing levels could hit 2100m. Wednesday is calling for another 15 to 20cm of snow.

Avalanche Summary

Some sluffing was observed in steep terrain. Three avalanches up to size 2.5 were triggered by cornice failures which pulled out slabs below. These were storm slab failures, with one slide stepping to ground. Several natural, skier remote, and skier accidental avalanches up to size 3.0 occurred in the Kananaskis Region and other areas in the southern Rockies on Sunday.

Snowpack Summary

New snow amounts were highly variable across the region with an average of 10cm new at treeline. Extensive wind transport due to strong SW winds is building cornices and wind slabs up to 60cm deep. These slabs are very sensitive where they overlie previously formed sun crusts. Solar aspects are sun crusted, which breaks down during the day with very limited solar input. The February surface hoar and the deeply buried basal facets seem to be coming alive again as we transition into Spring.

Avalanche Problems

Wind Slabs

Wind slabs continue to form with strong SW winds and are now up to 60cm deep. Natural and human triggered avalanches up to size 2.5 have occurred with many avalanches failing on the crust down 40-60cm. Slides may step down to deeper layers.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Cornices

Recent snow and strong SW winds, coupled with strong solar radiation at this time of year, are causing cornices to collapse. Cornices are triggering avalanches up to size 2.5 on underlying slopes, with some slides stepping to ground.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine.

Likelihood: Likely - Very Likely

Expected Size: 1 - 5

Persistent Slabs

The February surface hoar is buried 120-150cm at treeline. This interface is still hard to trigger, but it has come back alive in recent cornice triggered avalanches. The spring transition could see more avalanches stepping down to this layer.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6

Loose Wet

Intense spring-time solar radiation and warm temperatures will destabilize the snowpack through the day. Steep SE through W aspects are the most concerning.

Aspects: North, North East, East, South East.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4